Micro fluxgate sensor and method of manufacturing the same

Abstract

A micro-machining method of manufacturing a micro fluxgate sensor manufactured having an amorphous magnetic core includes forming lower coils of an excitation coil and a magnetic field detecting coil on a wafer, depositing a first insulating layer on the lower coils and forming an amorphous magnetic core, depositing a second insulating layer on the amorphous magnetic core and forming upper coils connected to the lower coils to complete the excitation coil and the magnetic field detecting coil, and covering the excitation coil and the magnetic field detecting coil with a protective film, and etching the protective film to expose a portion of the excitation coil and magnetic field detecting coil, thereby forming a pad.

1. A micro fluxgate sensor, comprising:
 an amorphous magnetic core formed on a wafer on which a seed layer is deposited; 
 an excitation coil wound around the amorphous magnetic core; 
 a magnetic field detecting coil wound around the excitation coil and the amorphous magnetic core; 
 a protective film formed on the excitation coil and the magnetic field detecting coil; and 
 a plurality of pads that are formed between the excitation and magnetic field detecting coils to external terminals to connect therebetween by etching the protective film, each of the pads exposing a portion of one of the excitation coil and the magnetic field detecting coil, and each of the pads corresponding to a via-hole in the protective film, 
 wherein each of the plurality of pads overlaps an upper and a lower portion of one of the excitation coil and the magnetic field detecting coil, and 
 wherein the upper portion is disposed above the amorphous magnetic core and the lower portion is disposed below the amorphous magnetic core. 
 
   
   
     2. The micro fluxgate sensor as claimed in  claim 1 , wherein the amorphous magnetic core is two bar-type amorphous magnetic core. 
   
   
     3. The micro fluxgate sensor as claimed in  claim 1 , wherein the amorphous magnetic core is formed in a rectangular ring shape. 
   
   
     4. The micro fluxgate sensor as claimed in  claim 2 , wherein the excitation coil is wound around the two bar-type amorphous magnetic cores in a substantially figure-eight pattern. 
   
   
     5. The micro fluxgate sensor as claimed in  claim 3 , wherein the excitation coil is wound around the amorphous magnetic core, which is formed in the rectangular ring shape, in a substantially figure-eight pattern. 
   
   
     6. A method of manufacturing a micro fluxgate sensor, comprising:
 forming lower coils of an excitation coil and a magnetic field detecting coil on a wafer; 
 depositing a first insulating layer on the lower coils and forming an amorphous magnetic core; 
 depositing a second insulating layer on the amorphous magnetic core and forming upper coils connected to the lower coils to complete the excitation coil and the magnetic field detecting coil; 
 covering the excitation coil and the magnetic field detecting coil with a protective film; and 
 etching the protective film to expose a portion of each of the excitation coil and the magnetic field detecting coil, thereby forming a plurality of pads between the excitation and magnetic field detecting coils to external terminals to connect therebetween. 
 
   
   
     7. The method as claimed in  claim 6 , wherein the amorphous magnetic core is two bar-type amorphous magnetic cores. 
   
   
     8. The method as claimed in  claim 6 , wherein forming the lower coils of the excitation coil and the magnetic field detecting coil on the wafer comprises:
 cleaning the wafer and forming a first seed layer; 
 forming a first photoresist film pattern on the first seed layer; 
 electroplating a coil material between the first photoresist film patterns; and 
 removing the first photoresist film pattern so that the coil material remains, thereby forming the lower coils of the excitation coil and magnetic field detecting coil. 
 
   
   
     9. The method as claimed in  claim 8 , wherein the coil material is copper (Cu). 
   
   
     10. The method as claimed in  claim 6 , wherein depositing the first insulating layer on the lower coils and forming the amorphous magnetic core comprises:
 etching the first seed layer on which the first photoresist film pattern is removed; 
 depositing a first insulating layer on the etched portion of the first seed layer and the lower coils; 
 bonding an amorphous magnetic film to the first insulating layer; 
 forming a second photoresist film pattern on the amorphous magnetic film; 
 removing the amorphous magnetic film, with a portion protected by the second photoresist film pattern remaining; and 
 removing the second photoresist film pattern to form the amorphous magnetic core. 
 
   
   
     11. The method as claimed in  claim 10 , wherein the amorphous material comprises cobalt (Co) having a DC permeability of about 100,000. 
   
   
     12. The method as claimed in  claim 6 , wherein depositing a second insulating layer on the amorphous magnetic core and forming upper coils connected to the lower coils to complete the excitation coil and the magnetic field detecting coil comprises:
 depositing a second insulating layer on the amorphous magnetic core and the first insulating film; 
 depositing a second seed layer on the second insulating layer; 
 forming a via hole extending to the lower coil through the second seed layer and the second insulating layer; 
 forming a third photoresist film pattern on the second seed layer; 
 electroplating the coil material between the third photoresist film patterns to connect the coil material with the lower coil through the via hole; and 
 removing the third photoresist film pattern so that the coil material remains, thereby completing the excitation coil and magnetic field detecting coil. 
 
   
   
     13. The method as claimed in  claim 6 , wherein covering the coils with the protective film and forming the pad comprises:
 etching the second seed layer from which the third photoresist film pattern has been removed; 
 depositing a third insulating layer on the etched portion of the second seed layer and the upper coil to form the protective film; and 
 patterning the protective film to expose a portion of the upper coil to form the pad. 
 
   
   
     14. The method as claimed in  claim 6 , wherein the amorphous magnetic core is formed in a rectangular ring shape. 
   
   
     15. The method as claimed in  claim 10 , wherein the amorphous magnetic core is formed in a rectangular ring shape. 
   
   
     16. The method as claimed in  claim 6 , wherein the excitation coil is wound around the amorphous magnetic core in a substantially figure-eight pattern. 
   
   
     17. The micro fluxgate sensor as claimed in  claim 1 , wherein the amorphous magnetic core comprises cobalt (Co) having a DC permeability of about 100,000. 
   
   
     18. The micro fluxgate sensor as claimed in  claim 1 , wherein the seed layer is in direct contact with the wafer and the lower portion of one of the excitation coil and the magnetic field detecting coil. 
   
   
     19. The micro fluxgate sensor as claimed in  claim 1 , wherein the seed layer is continuous along a direction perpendicular to a lengthwise direction of the amorphous magnetic core. 
   
   
     20. The micro fluxgate sensor as claimed in  claim 1 , wherein the seed layer is connecting horizontally adjacent lower portions of one of the excitation coil and the magnetic field detecting coil.